In recent years, techniques of using an automated tape bonding process when packaging integrated circuit chips have been developed in an attempt to replace other lead frame wire bonding methods currently used in packaging integrated circuit chips.
In a tape bonding process, an integrated circuit chip is directly bonded to a foil type lead frame that is usually less than about 0.5 mm in thickness. Such a technique is also referred to as tape automated bonding (TAB). In any event, in the usual tape bonding process, a bare copper, a gold or tin plated copper, or copper/plastic laminated tape is first prepared that has leads etched into it at positions corresponding to the gold plated bumps over aluminum bonding pads on the integrated circuit chip. The tape is then fed into an inner lead bonder, which is an apparatus having a thermode. A thermode is a heated instrument that presses the chip and tape together. The inner ends of the leads are bonded to the bumps on the integrated circuit chip by compressing them under the heated thermode in a single operation. Then the integrated circuit chip and bonded leads can be excised out of the tape for connection to a circuit board.
In the present state of the art of tape bonding, the high cost of mounting and testing of a chip at a single site on the tape provides a hindrance to the widespread implementation of this process into production. The cost of inspecting and testing a single integrated circuit chip at a site of lead frame is a significant portion of the manufacturing cost, as well as the chip mounting cost.
Therefore, it is an object of the present invention to provide a method of tape bonding integrated circuit chips that is more cost efficient and suitable for a mass production process.
It is another object of this invention to provide a tape bonding method for integrated circuit chips where two chips may be bonded to the same or different finger leads at a single site in a lead frame. The two chips can be either the same, different, mutually cooperative or mutually uncooperative.
It is yet another object of this invention to provide a tape bonding method for integrated circuit chips where two chips may be bonded to a single site of finger leads in a lead frame and then be inspected and tested in one operating step.
It is still another object of this invention to provide a tape bonding method for integrated circuit chips where two chips may be bonded in a face-to-face relationship to a single site of finger leads in a lead frame by using one inner lead bonder machine.